ABS Light

Tiny
MARKVELLUTATO
  • MEMBER
  • 2002 CADILLAC
  • V8
  • FWD
  • AUTOMATIC
  • 110,000 MILES
About a month ago my brake, abs, and traction control lights stayed on after starting. This would happen periodically but now they are always on. Had brakes checked and no problem. They did a computer check and codes C1214 and C1248 came up. Recommended I take it to GM Dealer for diagnosis. They did not want to mess with this problem.

Any idea what my problem might be before I pay dealer prices? Can I continue to drive the car with these lights on? Are the brakes fine? Thank you.
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Tuesday, July 5th, 2016 AT 7:12 PM

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Tiny
CARADIODOC
  • EXPERT
All cars have a "base" brake system. That is what you are using now. The anti-lock function is an option that is added to the base brake system. If the car has anti-lock brakes, traction control is another option that is added to that.

You are driving a car now that, in effect, does not have anti-lock brakes. You are simply missing that option. The issue that concerns me though is you are saying three warning lights are on. That tells me there is indeed a problem with your base brake system, even if it feels okay to you. There are up to three things that can turn on the red "brake" warning light. The least severe is low brake fluid in the reservoir. Not all cars have that switch to turn the warning light, but I am pretty sure yours does. If the brake fluid is low, do not add any. More on that in a minute.

Most cars use the red "brake" light to indicate the parking brake is on. Some cars use a separate "parking brake" light, but most do not. A stretched cable, or one that is rusted in the partially-applied position will not pull the parking brake pedal all the up to turn the switch off. To check for that, simply pull the pedal up with your toes. If the light goes off, have the parking brake cables checked.

All cars have two brake hydraulic systems. If there is a leak in one of them, you will still have two wheels working. Because there are unequal pressures being built up in the two systems when you press the brake pedal, a valve trips and turns on the warning light. That valve is real frustrating to reset on Ford products. On GM's and Chrysler's it is spring-loaded to center itself when you release the brake pedal. Sometimes they stick, and a solid quick jab on the brake pedal pops it free to recenter itself. On almost all front-wheel-drive cars, the left front and the right rear are on the same hydraulic circuit so you will always have one front brake working. (Those do eighty percent of the stopping on front-wheel-drive cars). GM has added an interesting wrinkle to that. There is a valve in the master cylinder that will block fluid flow to the circuit with the leak. That means you will not lose any brake fluid. If you pay very close attention, you might see a very slight wiggle in the steering wheel when you apply the brakes. The only other clue that there is a problem is the warning light. The car can appear to stop fine with only two brakes working. I do not know if that valve in the master cylinder is used on their cars that have anti-lock brakes.

Because of that valve, you will not lose brake fluid due to a leak. If the fluid level is low in the reservoir, the only other thing that can cause that is worn disc brake pads. As the pads wear, the pistons move out of the calipers to take up the slack. This is how all disc brakes adjust automatically over many thousands of miles. Brake fluid leaves the reservoir to fill in behind those pistons. Therefore, if the fluid is low, the first suspect is it's time for a brake job.

To squeeze the new thicker pads in, the pistons have to be pushed back into the calipers, and doing that pushes all the brake fluid back up into the reservoir. That is why no conscientious mechanic will ever top off the brake fluid during other routine services, like oil changes and inspections. When do-it-yourselfers fill the fluid, then perform a brake job later, all that fluid rushing back up there overflows and makes a horrendous mess on the floor. Brake fluid eats paint too.

I must mention too, to be safe, that it is extremely critical that you do not get the slightest hint of petroleum product mixed in with brake fluid. The repair for even one drop of engine oil, transmission fluid, or power steering fluid would likely exceed the value of your car. Professionals even wash their hands with soap and water before handling parts that contact brake fluid, to prevent getting fingerprint grease in the brake fluid.

Getting back to the red "brake" warning light, that has to be addressed because even though the brakes feel okay to you, that light is there because it may be the only way for you to know there is a problem. As a side note, if you were to get in a crash caused by the other guy running a red light, a lawyer or insurance investigator will find that your warning light was on and you were knowingly driving with less than perfect brakes. They will convince a jury that you were partly at fault because you were less able to avoid the crash, and they will be right.

The rest of the story is the Anti-Lock Brake Computer knows the red warning light is on. It does not know why, but the cause could prevent it from operating the anti-lock function properly, so the computer shuts the system off, sets a diagnostic fault code, and turns the yellow ABS light on to tell you. Likewise, the traction control system is added onto the ABS system, and since the ABS system is shut down, the traction control wont work either, so its warning light is on.

The bottom line is it is possible the entire soap opera will be solved with a brake job or the repair of a leak. Fix the base brakes, and the ABS will resume working. Get the ABS working, and the traction control will resume working.

There are plenty of other common problems on GM vehicles related to the anti-lock brakes, but while those will also cause the system to shut down, only the yellow ABS warning light will be on, and in your case, the traction control warning light. Those do not turn on the red "brake" warning light. That's why I am leaning toward a rather simple solution.
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Tuesday, July 5th, 2016 AT 10:41 PM

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